How many water molecules are present in one drop of water (volume , density )? (Express as , find to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
How many water molecules are present in one drop of water (volume $= 0.05\text{ mL}$, density $= 1.0\text{ g/mL}$)? (Express as $x \times 10^{21}$, find $x$ to nearest integer).
Answer: 2
💡 Solution & Explanation
$\text{Mass} = 0.05\text{ g}$. $\text{moles} = 0.05 / 18 \approx 0.00277 \text{ mol}$. <br>$\text{Molecules} = 0.00277 \times 6.022 \times 10^{23} \approx 1.67 \times 10^{21}$. <br>Rounding to nearest integer, $x = 2$.
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